class get_c_str {  var $str;  var $start_str;  var $end_str;  var $start_pos;  var $end_pos;  var $c_str_l;  var $contents;  function get_str($str,$start_str,$end_str){     $this->str = $str;     $this->start_str = $start_str;     $this->end_str = $end_str;     $this->start_pos = strpos($this->str,$this->start_str)+strlen($this->start_str);       $this->end_pos = strpos($this->str,$this->end_str);     $this->c_str_l = $this->end_pos - $this->start_pos;     $this->contents = substr($this->str,$this->start_pos,$this->c_str_l);     return $this->contents;  }  }//使用方法$url = ‘http://www.xiaodoubi.com‘;$data = file_get_contents($url);$get_c_str = new get_c_str;$content = $get_c_str -> get_str($data,‘<p class="message">‘,‘</p>‘);echo $content;